This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Under a blazing sun, workers crouch on a shrinking island off India's southern coast, threading bright green seagrass shoots onto wooden frames before anchoring them to the ocean floor. Restoration work on Kariyachalli Island aims to rebuild its natural defenses with artificial reefs, transplanted corals and seagrass meadows to slow erosion and protect the mainland from surging seas.
"If you are not able to provide that resilience, you are absolutely at the mercy of vulnerabilities of storm surges, cyclonic storms or sea-level rise and also erosion," senior state official Supriya Sahu told AFP. traveled by boat to the protected island after being granted exclusive access by the foreign ministry. Kariyachalli, part of a chain of 21 islands in southern Tamil Nadu state, has lost more than 80% of its landmass over the past half-century and could disappear entirely by 2036 if erosion is left unchecked. Government estimates show Kariyachalli shrank from 20.85 hectares (51.5 acres) in 1969 to just 3.14 hectares (7.8 acres) last year.
The coral reefs in the Gulf of Mannar, where Kariyachalli and other islands are located, also play a vital role in softening the impact of natural disasters, such as the 2004 Indian Ocean tsunami. More than 8,000 people were killed in Tamil Nadu during the tsunami, but marine scientists say these ecosystems acted as a crucial natural barrier and prevented a much larger disaster. "This was because these tiny islands, seagrass and coral beds absorb the impact," said K.
Diraviya Raj, an associate professor at the Suganthi Devadason Marine Research Institute. The Gulf of Mannar is among Asia's richest marine environments, home to coral reefs, endangered dugongs and hundreds of fish species. But decades of human activity and climate change have steadily weakened the ecosystem.
Coral mining in the 1960s and 1970s severely damaged reefs around the islands. Pollution, overfishing and coral bleaching caused by warming seas have also added pressure. Around Kariyachalli, reef cover fell from roughly 500 hectares (1,200 acres) in 2005 to 197 hectares (490 acres) in 2021.
The restoration, part of a $4.79 million state conservation program, includes the deployment of about 8,500 artificial reef modules around the island. The bulky structures, each weighing several tonnes, are being lowered into carefully selected locations around Kariyachalli. Designed using data on seabed conditions, currents and wave patterns, they are intended to break the force of incoming waves while creating new surfaces for corals to colonize.
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